Tunnelblick Stable Release(A stable release is a version that has been tested as thoroughly as possible and is as reliable as we can make it. It usually does not have all the new features of a beta release, but may be more reliable.) For use on OS X 10.4 - 10.8 ("Tiger", "Leopard", "Snow Leopard", "Lion", and "Mountain Lion"), Intel or PowerPC, 32- or 64-bit.